Add release changes top-level summary

release notes/v0.50.0.md

@@ -1,12 +1,13 @@
-k6 `v0.50.0` is here 🎉! This release includes:
-
-- (_optional_) `<highlight of breaking changes>`
-- `<Summary of new features>` (_one or multiple bullets_)
+k6 `v0.50.0` is here 🎉! 
 
+This release:
+- Adds support for uploading files from the browser module.
+- Introduces the `options.cloud` option.
+- Stabilizes the previously experimental timers module as the `k6/timers` module.
+- Brings JSON Web Key support to the `k6/experimental/webcrypto` module.
 
 ## Breaking changes
 
-- `#pr`, `<small_break_1>`
 - [websockets#60](https://github.com/grafana/xk6-websockets/pull/60) allows manually setting the `name` tag, which also overwrites the `url` tag with the `name` value. This change makes it consistent with the logic that was implemented in k6 v0.41. Thanks, @mkadirtan for contributing!
 
 ### Browser APIs to Async